EEG abnormalities and epilepsy in autistic spectrum disorders: Clinical and familial correlates
Introduction
Autistic spectrum disorders (ASD) are devastating conditions with an onset in early childhood and core symptoms of varying degrees involving communication and social and cognitive development, and usually sparing gross motor development. In 1943, Kanner was the first to describe the case of an autistic individual who developed epilepsy [1]. The frequency of epilepsy in autism ranges from 4% to 42% according to different studies [2], [3], [4], [5], [6]. It is known that a significant majority of patients with ASD without seizures have interictal epileptiform EEG abnormalities (IIEAs) on routine EEG studies [5], [6]. The incidence of IIEAs in autistic individuals was found to be between 6% and 74% [5], [6], [7], [8].
Previous studies have reported age, mental status and neurological findings as risk factors for epilepsy in ASD. There is a bimodal age distribution of seizures in autism: one peak occurs before 5 years of age and the other in adolescence after age 10 [7], [9], [10]. Individuals with ASD who have profound mental retardation and/or cerebral palsy are at high risk for epilepsy [5], [7]. However, whether there are other factors associated with epilepsy and epileptiform EEG abnormalities in ASD remains unknown. Indeed, although not previously shown, the factors associated with epilepsy and IIEAs may differ. The aim of this study was to examine the characteristics of EEG findings and epilepsy in ASD subtypes and the association between epilepsy and EEG abnormalities and clinical, psychiatric, developmental, and familial risk factors.
Section snippets
Methods
Fifty-seven patients between the ages of 2 and 18 years who were diagnosed with ASD (autism, Asperger syndrome, Pervasive Developmental Disorder Not Otherwise Specified [PDD-NOS], high-functioning autism [HFA]) according to DSM-IV [11] criteria were included in the study. For all patients, 1-hour recordings of sleep and/or awake EEGs were obtained. Patients with a diagnosis of schizophrenia, schizophrenic disorder or any other psychotic disorder, Rett syndrome, childhood disintegrative disorder,
Results
The mean age of the total sample was 82 ± 36.2 months (range: 30–192 months). The mean age of children with autism was 79 ± 32 months, whereas the mean ages of those with PDD-NOS and HFA were 87 ± 42.7 and 108 ± 44.4 months, respectively. Fifty-nine percent of children with autism were under the age of 6 years, whereas 73% of patients with PDD-NOS were above 6 years of age. Forty-nine patients (86%) were boys and 8 (14%) were girls. Thirty-nine patients (68.4%) were diagnosed with autism, 15 (26.3%) with
Discussion
In this study, children with ASD were evaluated in terms of psychiatric, systemic, and familial characteristics. Most of the previous studies of EEG findings and epilepsy in children with ASD were performed in children with autism, and associations other than age, mental status, and neurological findings were not examined. We question whether the psychiatric, systemic, and familial characteristics of patients with ASD have an influence on the presence of epilepsy and/or IIEAs.
The prevalence of
Conclusion
The frequencies of epilepsy and IIEAs are higher in children with autism compared with the normal population. However, the possible association of epilepsy/IIEAs with factors other than cognitive level and age of patients has not been investigated thoroughly. Clinical medical factors associated with IIEAs such as asthma/allergy and neurobehavioral correlates such as hyperactivity were prominent findings in our study. Studies with larger samples focusing on developmental, psychiatric, medical,
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2015, Epilepsy and BehaviorCitation Excerpt :Similarly, a longitudinal study looking into the incidence of epilepsy in ASD reported that the presence of epilepsy was independently associated with a broader autism phenotype in relatives (i.e., subthreshold autistic traits) [21]. Studies also show that a family history of epilepsy is associated with an increased risk of epilepsy in those with ASD [4,20,29] which is not surprising given the heritability of some of the epilepsy syndromes; however, at least one study did not find this to be true [21]. A few papers have considered other risk factors or associations for the occurrence of epilepsy in ASD, including pre- and perinatal issues, developmental problems, and family histories (e.g., presence of psychiatric and neurological disease), but most of the studies had samples that were too small to draw reliable conclusions.